Due to an increasingly crowded frequency spectrum, electronic device manufacturers have relatively recently become interested in the integration of radios capable of frequencies of 60 GHz and above. Millimeter-wave (mm-wave) radios integrated into electronic devices may provide short range, high-speed transfer of data with data rate in the order of several Gigabits per seconds (Gbps).
One problem with attaching mm-wave radio dies to stacks of substrate materials is that the mm-wave dielectric material used in the substrate can be relatively expensive as compared to other materials, hence limiting the mass-adoption of such radios in consumer electronics. Additionally, traditional substrate materials can exhibit poor electrical performance (e.g., electrically lossy) at mm-wave frequencies as compared to other types of dielectric materials.
There are general needs for adding mm-wave radio dies to a stack of substrates.